A liquid electrophoretic (LEP) ink (also known as electro-ink) is a liquid ink that aims to combine advantages of electronic printing with the qualities of liquid ink. LEP inks enable digital printing by electrically controlling the location of print particles. LEP inks may be supplied as a concentrated paste that is loaded into a LEP printer (also referred to as press) in cartridges in a “clean hands” operation. Inside the press, the LEP ink is diluted with a carrier liquid (also referred to as solvent) to form a fluid mixture of carrier liquid and electrophoretic colorant particles ready for printing. Oil may be used as carrier liquid for LEP inks.
Ink concentration of a LEP ink is an important parameter that influences print quality. For example, variation of LEP ink concentration during a print run may affect print quality.